Fall will be sticking its frigid fingers into D.C.'s airspace this week, with high temperatures in the mid-60s possible Thursday and beyond.

Low temperatures on Thursday night could be in the 40s (shown in purple) in the mountains. (NWS)

With meteorological summer having ended on August 31, it's just a matter of time before Beltway circlers have to man up and accept the coming winter shivers. But it's been easy to forget that recently, what with the sumptuous sunshine and tropical-style downpours of the past week.

No more: Autumnal temperatures in the 40s to 60s may have you soon reaching for the nearest Cosby sweater... or something even more odious. "It might be Snuggie weather by the end of the week," says ABC7 meteorologist Steve Rudin.

Today will be fine, with only a penny's worth of a chance of showers and plenty of warm weather (forecast) to display that astronaut-fighting-a-bear T-shirt you may have picked up at the Adams Morgan Day Festival. And Tuesday will be one of the "best, brightest days" this week, says Rudin. On Wednesday, though, a cold front pushes into D.C., swatting away the heat and replacing it with a dry, lifeless mass of northern air.

The good news is that with little moisture accompanying this new development, locals won't have to put up with more of this foolishness:

The bad is that nightly temperatures will likely drop into the 40s in the mountains and possibly elsewhere. Daytime in D.C. will probably hover in the mid-60s on Thursday and Friday. So if you've procrastinated about planning that beach vacation until this weekend, you're probably looking at a miserable few hours on damp sand the temperature of the Safeway seafood case.

So is this the death of summer? Maybe not, says Rudin, but it's close. "I think we'll have a few more days" when it feels like it's truly summertime, he says. "But they will be spread out farther and farther apart."